Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 23,508	$ 20,973
Unrealized gains and losses on securities available for sale:
Net unrealized gains arising during the period	771	7,094
Reclassification adjustment for gains included in net income	0	(57)
Total	771	7,037
Unrealized gains (losses) on derivatives	55	(421)
Amortization related to post-retirement obligations	32	99
Total other comprehensive income	858	6,715
Total comprehensive income	$ 24,366	$ 27,688

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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